End of US-Russia nuclear deal ‘grave moment’: UN chief

UN chief Antonio Guterres on Wednesday (Feb 4, 2026) urged the United States and Russia to quickly sign a new nuclear deal, as the existing agreement is set to expire at “a critical moment for international peace and security”.

The New START treaty expires on Thursday (February 5, 2026), formally releasing both Moscow and Washington from a raft of restrictions on their nuclear arsenals.

“For the first time in more than half a century, we face a world in which there are no restrictions on the strategic nuclear arsenals of the Russian Federation and the United States of America,” Mr Guterres said in a statement.

The UN Secretary General added that New START and other arms control treaties have “drastically improved the security of all peoples”.

“This dissolution of decades of achievement could not come at a worse time – the threat of nuclear weapons is at its highest in decades,” he said, without elaborating.

Mr Guterres urged Washington and Moscow to “return to the negotiating table without delay and agree on a successor framework”.

Russia and the United States together control more than 80% of the world’s nuclear warheads, but arms deals are drying up.

New START, first signed in 2010, limited each side’s nuclear arsenal to 1,550 deployable strategic warheads — a reduction of about 30% from the previous limit set in 2002.

It allowed each side to conduct on-site inspections of the other’s nuclear arsenal, although these were suspended during the Covid-19 pandemic and have not since resumed.